Method of ore separation



Patented July 23, 1935 v 2,008,928 nmrnon or one snmna'rron Joseph P. Ruth, Jr., and Frederic A. Brinker, Denver, 0010., assignors to The Ruth Company, Denver, (him, a corporation of Colorado No Drawing.

Application August 23, 1932, Serial N0. 630,095

4 Claims. (oi. 209-166) I This invention relates to improvements in the froth flotation treatment of ores. The object of this invention is to materially improve the recovery of the minerals in their respective concen- 5 trates, and also to improve the purity of the concentrates, or as is usually stated, improve the grade of each respe'ctive concentrate in its own mineral content. This invention relates to the treatment of ores before the flotation step. It has long been known that cyanide is valuable as a depressing agent. In ores where zinc sulfide is present, it is well known that zinc cyanides are formed; In many cases satisfactory metallurgy has been accomplished by this combination. However, repeated experiments have shown that this invention, which consists in eliminating the sulfate radical when conditioning the ore pulp with zinc cyanide, gives results that were never even remotely approached where the sulfate. or the S04 radical was retained. Zinc cyanide has been commonly manufactured, both within the pulpv and without, by combining sodium cyanide or potassium cyanide with zinc sulfate. The well known reaction products are zinc cyanide and sodium sulfate.

This invention consists of treating a pulp with a zinc cyanide from which the sulfate radical has been removed. We have discovered that one of the most detrimental sulfates is the sulfate produced in making the most excellent inhibitor, zinc cyanide. We have found that this particular kind of zinc cyanide can be made by using a zinc salt that will react with sodium or potassium cyanide which does not form a sulfate. For example: The deleterious results are not experienced when sodium cyanide and zinc nitrate are mixed together forming zinc cyanide and sodium nitrate. However, other salts may be used in this process, providing that they are not sulfates. A satisfactory compound can be made using zinc sulfate and sodium cyanide which consists'of adding the two together and making an insoluble zinc cyanide which can be washed free of the soluble sodium sulfates. This compound we have found to be valuable either in its soluble or insoluble state, or as a mixture of both, but it must be made up prior to its addition to the pulp, since the soluble sodium sulfate must be washed or filtered of! and disposed of and not permitted to get into the pulp where complete inhibiting of the sulfides is desired. 7

The following is a description of the use of this invention: To an ore containing lead sulfide, copper sulfide, zinc sulfide and iron sulfide, a quantity varying from one-quarter of a pound to one pound per ton of ore of this sulfate radical free zinc cyanide is added, to the feed water, or to the feed end of the grinding mill which is to liberate the sulfides contained in the ore. This compound when free from sulfates has a most potent eifect in forming zinc cyanide surfaces on the total content of the sulfides mentioned above, preventing the oxygen from oxidizing the sulfides and from making deleterious sulfates in the mill. After the grinding operation, practically complete inhibiting of the copper, zinc and iron sulfides is effected and little or no sulfate remains in the ore pulp. Since the lead is not inhibited, a satisfactory frother is added which floats practically all of the lead sulfide. The promoter most commonly used is a di-substituted dithiophosphate known to the trade as "Aerofloat The copper is -then reviviiled by either lead nitrate or ammonia, and floating with a satisfactory frothing oil. The zinc is then promoted and floated with a satisfactory promoter and frothing oil, there will only remain then, iron which has been completely inhibited throughout the entire operation because of the elimination of the sulfate radical and other nonfiotable materials.

What is claimed is:

1. In the flotation separation of ores containing sulfides, the-step of conditioning the same prior to flotation, with a zinc cyanide from which the sulfate radical has been removed.

2. In the flotation separation of ores, the use as an inhibitor of the sulfides, a zinc cyanide from which the sulfates formed in its production have been eliminated.

3. In differential froth'flotation separation of complex ores, removing the soluble sulfates in ground vore pulp, repulping and adding zinc cyanide free from sulfates to the repulped ore and subjecting the resulting pulp to differential froth. flotation treatment.

4. The method of froth flotation separation of ores which comprises the addition to the ore and water in a grinding mill in which complex sulfide ores are ground of a quantity of sulfate radical free zinc cyanide in an amount varying from one quarter to one pound to each ton of ore.

JOSEPH P. RUTH, JR. FREDERIC A. BRINKER. 

